Succubus

Poison is one of the bosses that Dante faces in Limbo City. She is a 1,200 year old succubus demon, and the toxins she secretes are used as the "secret ingredient" of Virility, helping to control humanity as per Mundus's wishes.

Story
Upon meeting her, Dante calls her the "secret ingredient" to Virility. She and Dante continue a small dialogue wherein she recalls Dante as the "son of Sparda and Eva the whore" and says that she's twelve-hundred years old. Poison then vomits at Dante and begins fighting him shortly afterward.

Much of Poison's dialogue in the ensuing boss battle consists of berating Dante or threatening to eat him and desecrate his corpse.

Upon defeating her, Dante acquires the Eryx Gauntlets.

Powers & Abilities
Poison is an ancient demon. Her most obvious ability is her acidic vomit which she secretes with projectile efficiency. Her size and mass gives her enough strength to smash the platforms that Dante stands on. She can block many of Dante's Rebellion attacks, though she is far from invulnerable. Like all powerful demons, she can control Malice to a limited degree while in Limbo.

Given her advanced age and boasts of invincibility, Poison's superhuman stamina and vitality has given her a greatly extended life span and resistance to injury.

Strategy
Once she begins fighting, her attacks consist of a some sweeping or crushing attacks with her hands, a roar that knocks Dante back, and an attack that coats the entire floor with vomit for about ten seconds. Dante can attempt to use only aerial attacks to avoid stepping in the vomit, or he can use his Angel Lift to travel to another platform. Poison's weak spot is a red carbuncle on her head that is covered by her flaccid body. Dante can damage her arms and body, but can deal significantly more damage by staggering her and attacking the weak spot.

After depleting enough health, Dante can use his grapple to briefly incapacitate Poison; and then use his grapple again while she is incapacitated to pull out one of the wires supporting her from the back. After pulling at the wire a few times, Dante punches Poison in the face and she falls into a large pool of what is presumably her own vomit flooding the boss room.

As Dante leaves, Poison emerges from the ground and begins trying to kill him again in a rushing river. Using the Lift and Grapple abilities, Dante forces the demon into a giant industrial fan, finally killing her.

Background
A poison is a substance, lethal or otherwise, that causes a disturbance within an organism when introduced.

A succubus is a female demon who enters a man's dreams, appearing as an attractive woman to seduce them and drain their strength through sexual intercourse. Due to pop culture, many believe the succubus to be a sexually attractive woman personafied by the likes of Morrigan Aensland of Darkstalkers or Jennifer Check of Jennifer's Body, but traditionally, a succubus is a grotesque demon, which Poison is more in keeping with.

Poison's appearance is based on a centipede or possibly a caterpillar. The bite from certain species of centipedes can cause swelling, chills, fever, and even anaphylactic shock if the centipede is large enough. In addition to being the larval form of a butterfly, "caterpillar" can also mean a person who extorts money from people or otherwise uses people for their personal gain.

Trivia

 * To incapacitate Poison, Dante utilizes a running two-legged kick to her face. This is almost the same dropkick Nero uses on Dante in Devil May Cry 4 (coined the Rainbow) when they first meet.
 * Just as the Hunter in the Captivate Trailer was the first character to speak Sparda's name, Poison was the first character to confirm Eva's name via leaked boss footage. Both boss characters have specifically referred to Eva as a "whore".
 * Being the secret ingredient in a beverage, Poison's situation closely mirrors that of a Futurama episode where The Planet Express crew discovers that the secret ingredient of the fictional soda drink Slurm contains fluids from the body of a creature called Wormulon Queen.
 * Like Virility, Slurm is also highly addictive.
 * Poison's character model has about 500 joints inside it.
 * Poison is considered by fans to be the most vulgar & foul-mouthed demon in the series ever.
 * A possible nod to being based on a caterpiller, in the demo she looks at Dante and says "Who are you?" which the caterpiller from Alice in Wonderland asked to Alice.
 * Race Davies, the actress who portrays Poison, also played Whiptail in Ninja Theory's Heavenly Sword.